How does light scattering by pores affect the transparency of optical ceramics?

In the context of optical ceramics, light scattering caused by pores significantly reduces transparency, rendering materials opaque or white in appearance.1

While many ceramics are wide-band-gap insulators capable of transmitting light, this transparency is only achieved when the material is free of internal scattering centers. Pores act as these centers because they create interfaces where light is scattered, preventing the material from appearing clear. Consequently, achieving high transparency in polycrystalline ceramics requires sintering the material to full optical density to eliminate porosity. For example, the development of translucent alumina was a major breakthrough that relied on using sintering aids to reach this necessary density, allowing the material to transmit light effectively.1